Gabapentin

How it works

It binds the alpha-2-delta subunit of voltage-gated calcium channels, reducing presynaptic calcium influx and the release of excitatory neurotransmitters.

Prescribing in practice

• Gabapentin is a controlled drug with recognised abuse potential and risk of fatal respiratory depression, especially when combined with opioids or other CNS depressants or in respiratory compromise.
• Doses require titration to minimise sedation and dizziness, and the dose must be reduced in renal impairment as it is cleared unchanged by the kidneys.
• Withdraw gradually to avoid rebound seizures and a discontinuation syndrome.

Monitoring

Monitor for sedation, mood or behavioural change including suicidal ideation, and review renal function as a guide to dosing.

Counselling the patient

• Do not stop suddenly; the dose should be tapered under medical supervision.
• Avoid alcohol and be cautious with driving until you know how it affects you.
• Report low mood, thoughts of self-harm or excessive drowsiness.

Evidence & guidelines

MHRA reclassified gabapentin as a controlled drug and has warned of the risk of respiratory depression when combined with other CNS depressants.